Pelamis
Made in Scotland, but it’s a Portuguese consortium, led by Enersis, who are to build the world’s first commercial wave farm off the north coast of Portugal. The initial phase will consist of three Pelamis P-750 (750 kW) machines, giving a total installed capacity of 2.25MW at a cost of £8 million. If all goes well, the number will be boosted to 30 or 40 machines.
The Pelamis prototype has been operating at the Orkney test centre since August 2004. No major issues of durability or corrosion were found during the staged test programme over the year. The US Electric Power Research Institute (EPRI) have given it a positive independent assessment, considering that it’s the closest to commercial delivery of current wave energy machines. Read the EPRI report here
The EPRI assessment for the US government envisages tens of GW wave energy off shore for Massachusetts and other states. Wave energy has the potential to become one of the lower cost forms of generation in the longer term, it is believed. Ocean Power Delivery who have developed Pelamis say the power from the Portuguese installation will be a quarter the current cost of solar photovoltaic power and half the cost of the first wind power machines.
Each Pelamis ‘snake’ is made of four segments, hinged both horizontally and vertically, to permit sideways and up-and-down movement. Each segment in the P-750 will be similar in size and length to a train carriage. When it’s bent and twisted by the waves, pistons force oil through hydraulic chambers connected via valves to give a smoothed flow that drives a dynamo generator.
The Pelamis snake is moored to keep it head-on into the waves. Survivability is vital so the design allows Pelamis to dive through storm waves that are ten times higher than the average waves (100 times more power). Efficiency is quite low, under 10%, but that is not so important when the waves off Atlantic facing coasts carry some 60kW per metre.
Picture from Ocean Power Delivery, whose website gives further information.
